Purification of surface-associated urease from Helicobacter pylori

Helicobacter pylori colonizes the human gastric mucosa and produces large amounts of urease. The enzyme was extracted from the bacteria by distilled water and purified by gel-permeation (Sephacryl S-300), anion-exchange chromatography (Mono Q) and a second gel-permeation (Superdex 200). Urease enzyme activity was detected with a spectrophotometic assay based on phenol red. The optimal pH for anion-exchange was 6.9. The recovery of urease was 55–75%, purity 93–98% and the overall protein recovery 0.8–1.4%. The urease in the final extract still had enzymatic activity and showed the typical subunits of Mr 66 000 and Mr 30 000 when subjected to sodium dodecyl sulfate–polyacrylamide gel electrophoresis.